The Reason For The Increased Threshold Switching Voltage Of Sio2 Doped Ge2sb2te5 Thin Films For Phase Change Random Access Memory

This study examined the threshold switching voltage (V-T) of 150 nm thick SiO2 doped Ge2Sb2Te5 (SGST) films for phase change random access memory applications. The VT of the SGST films increased from similar to 0.9 V (for GST) to similar to 1.5 V with increasing SiO2 content. The optical band gap and Urbach edge of the SGST films were similar regardless of the SiO2 concentration. The dielectric constant decreased by similar to 37% and the electrical resistivity increased by similar to 19%. The increase in VT of SGST films is associated with an effective increase in electric field and the decreased generation rate caused by impact ionization. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3232237]